A middle-aged man with scrotal and perineal pain.

A 53-year-old man, with a history of metastatic lung cancer treated with chemotherapy, presented with a high fever and in poor general condition in September 2008. He was found after slipping and falling in a toilet and was therefore admitted to hospital. He appeared to be suffering acute sepsis and a physical examination revealed tenderness over his scrotum and perianal region. An X-ray of his pelvis (Fig 1) was performed to look for fractures. What was he suffering from? Computed tomography (CT) of his lower pelvis (Fig 2) was also performed to delineate the extent of involvement.